....Robert Bowers was angry at Jews. But the 46-year-old alleged killer of at least eleven people in a Pittsburgh synagogue seemed most angry at Jews for one particular reason: They were helping Muslim refugees flee to safety in America.

In posts on Gab, the social media network favored by white supremacists, Bowers fixated on HIAS, the Jewish group that helps refugees resettle in the United States, including many Muslim refugees from the Middle East and Africa. Earlier this month, Bowers wrote that HIAS wants “to bring in hostile invaders to dwell among us.” Another white supremacist’s post on Gab that Bowers reposted read: “It’s the filthy EVIL jews Bringing the Filthy EVIL Muslims into the Country!! Stop the kikes then Worry About the Muslims!”

....Earnest was being questioned by the FBI and homicide authorities. San Diego Sheriff William Gore said authorities were poring over his social media accounts and a letter that Gore described as a "manifesto" posted online around the time of the attack
Gore said officials were working to verify the posting's authenticity and did not offer details on any motive. But the letter supposedly details the shooter's hateful motivations and his reasons for targeting members of the Jewish faith....

....Gore, the sheriff, said Earnest was also being investigated in connection with an arson at a mosque in nearby Escondido last month. In that incident, a fire broke out at 3:15 a.m. on Sunday, March 24, at Dar-ul-Arqam mosque, also known as the Islamic Center of Escondido.

The suspect in that attack left behind a note referencing the terrorist attacks at two mosques in Christchurch, New Zealand, that killed 50 worshippers in mid-March. The letter that investigators are investigating related to Saturday's attack also claims responsibility for the arson at Dar-ul-Argam....